PostgreSQL 13 Beta 1 Release Announcement Draft

Hi,

Attached is a draft of the release announcement for the PostgreSQL 13
Beta 1 release this week.

The goal of this release announcement is to make people aware of the new
features that are introduced in PostgreSQL 13 and, importantly, get them
to start testing. I have tried to include a broad array of features that
can noticeably impact people's usage of PostgreSQL. Note that the order
of the features in the announcement are not in any particular ranking
(though I do call out VACUUM as being one of the "most anticipated
features"), but are my efforts to try and tell a story about the release.

Please let me know your thoughts, comments, corrections, etc. and also
if there are any glaring omissions. I know this is a bit longer than a
typical release announcement, but please let me know your feedback
before the end of Wed. May 20 AOE (i.e. before the release ships).

Thanks for your review!

Jonathan